Locomotives have a large prime mover, usually a 12 or 16 cylinder diesel motor that typically drives, on one end, a DC and/or AC main generator and/or an auxiliary generator; and also at least one air compressor. The main generator produces electricity that is transmitted to electric traction motors that sit on top of each axle and provide power to the wheels. The auxiliary generator provides the power for appliances on the locomotive, such as headlights, fans, and the like. The compressor provides air pressure for operating the air brakes. The cab of the locomotive includes various components, including an electrical cabinet; main and auxiliary generators, diesel motor/engine, and an air compressor.
About 99% of the locomotives in service today are made by two manufacturers: Electro-Motive Diesel, Inc. (EMD) and General Electric (GE). EMD makes two-stroke diesel locomotive motors, while GE makes four-stroke diesel locomotive motors. Locomotives manufactured currently may start at about 3000 horsepower, but the locomotives in service today still include a great many that are of lesser horsepower. The present disclosure relates to the retrofitting of two-stroke EMD locomotives, and in particular EMD locomotives of nominal 2000 horsepower or less, and higher horsepower EMD locomotives that are being downgraded to nominal 2000 horsepower or less. However, it will be understood that the structures and methods of the disclosure may be adapted to other motor or engine systems, including marine motors or larger locomotives, or four-stroke motor systems.
The United States Environmental Protection Agency (EPA) regulates locomotive emissions, and such regulations have provisions relating to the rebuilding of locomotives. In general, “rebuilding” typically involves replacing the motor pistons and liners. Unlike an automobile motor, a locomotive diesel motor has removable pistons and liners which are pulled out and replaced with new ones when the locomotive is overhauled.
Locomotives are typically overhauled every five to seven years, so within a time frame of that length most of the locomotives in the US are going to have to become EPA compliant. It is a lot easier to do that with a four-stroke than a two-stroke motor, but since most of the lower horsepower locomotives in existence utilize two-stroke engines built by EMD, the present disclosure is primarily directed to application with 2000 horsepower or less two-stroke EMD locomotives.
Two prior techniques are currently utilized for bringing rebuilt locomotives into compliance with the EPA regulations. One approach has been to remove the diesel motor, both generators and the compressor and replace them with two or three 750 horsepower gensets, which are basically standby power plants, such as hospitals use, which are provided with AC electrical generators. The electricity is converted to DC for powering the traction motors, and remains AC for providing power to the appliances, which may further include a new AC-powered compressor. A new electrical cabinet may be required as well, and the selling price on these units has a cost in the $1.4 million to $1.7 million range, depending on whether it is a two or three genset locomotive.
Another approach involves the installation of a single 2250 horsepower Detroit Diesel motor with a new AC generator, a new electric compressor and a new electrical cabinet. The cost is about the same as the previously described three genset unit, but there are fewer moving parts in the rebuilt unit.
What is desired is a less expensive alternative for retrofitting a locomotive. The present disclosure accomplishes this by enabling a locomotive engine to be retrofit without replacing the generator and some of the electrical components, thus achieving considerable savings. This has not been accomplished in the past due to the incompatibility of EPA compliant diesel engines with the generator and related electrical components of the locomotive to be rebuilt.